The subject matter of the present invention is titanium(IV) dialkoxy-bis-acetylacetonates which are soluble in water or whose solutions are miscible with water without incurring degradation.
It is known to use titanium chelates, especially titanium(IV) bis-acetylacetonate, as catalysts, crosslinking agents or coating materials. In contrast to the use of alkyl titanates, it is possible to operate in the presence of water, since the alcoholic solutions of titanium(IV) dialkoxybis-acetylacetonates used in practice are compatible with water. These solutions are generally prepared by the reaction of one mole of a titanic acid tetraalkyl ester, especially tetraisopropyltitanate, with two moles of acetylacetone; that two moles of alcohol that are liberated in the reaction are not distilled away but serve as solvent for the reagent, which is also known as titanium acetylacetonate. Accordingly, the common commercial solutions of titanium acetylacetonate are generally about 75% solutions of this chelate in the alcohol corresponding to the alkoxy group.
In the fields in which titanium acetylacetonates are employed, there is an increasing need to use this reagent in low concentrations, chiefly in concentrations of less than 5%, and to replace the organic solvent largely with water.
The obvious solution of this requirement, namely to dilute the above-named alcoholic solutions of titanium acetylacetonate in water, runs up against the following difficulty: If these alcoholic solutions are simply diluted with water, precipitates form. To prevent the occurrence of such precipitation, the proposal has already been made to add an equal amount by weight of 10% acetic acid to the solution before adding the water, and then to add 13 times the amount of a 1:1 mixture of isopropanol and water, and only then to dilute the solution with water. Other proposals suggest either first to add twice the amount of methyl ethyl ketone and then stir the water in slowly or to add the water in the form of a mixture of 7 parts water and 3 parts isopropanol. All of these proposals are either too costly and time-consuming, or they increase the organic solvent content, or they do not provide a satisfactory solution of the problem.
The problem therefore existed of preparing titanium acetylacetonate solutions which can be diluted to solutions of less than 5% by the simple addition of water, without incurring turbidity in the solutions.